Apparatus for electric welding.



H. R. WOODROW.

APPARATUS FOR ELECTRIC-WELDING APPLICATION FILED MAR/I3. I9I5.

2 SHEETSSHEET I.

ghi/tzeoow J7! Svwwwtoz Patented July 6, 1915.

H. R. WOODROW.

APPARATUS FOR ELECTRIC WELDING. APPLICATION FILED MAR. I3. ms.

1 ,145,642. I Patented July 6, 1915.

2 SHEETSSHEET 2.

I I 25 7 Z4 Z3 27 I lvwa z %1 alto away Y AM/ M HARRY woonRow, on NEWYORK,

N. Y., ASSIGN-OR TO THOMAS E. MURRAY, 01? NEW YORK, N. Y. I

APPARATUS FOR ELECTRIC WELDING.

Specification of Letters Patent; 7

Patented July 6, 1915..

Application filed March 13, 1915. Serial No. 14,193.

To all whom it may concern Be it known that I, HARRY R. WooDRow, acitizen of the United States, resldlng at New York, in the county of NewYork and State of New York, have invented a "certain new and usefulImprovement in Apparatus for Electric Welding, of which the following isa specification.

The invention relates to electric welding, and consists in an automaticapparatus embodying an electric motor energized by the welding current,which motor controls the duration of said current. Means are providedwhereby an initial duration of the Welding current is established, andthereafter this duration is controlled by the variations in resistanceat the welding electrodes, which variations affect the speed of themotor to vary the duration of the cur-.

rent correspondingly to the resistance changes.

In the accompanying drawings Figure 1 illustrates generally myapparatus. Fig. 2

is an elevation, and Fig. 3 a plan view of a device for determining theduration of the welding current.

Similar letters, and numbers of reference Referring first to Fig. 1: Aand B are two bars to be welded together at their ends. The bar B isheld in a metal screw clamp O which is immovably held upon a plate D ofinsulating material which rests upon the base E, by means of aninsulated screw bolt F. The bar A is held in a similar screw clamp Gwhichis slidable upon said plate D. On 7 the clamp G is a "projectingstud H.

I is a bell crank lever pivoted in a suitable fixed bracket J. Betweenthe upright arm ofsaid lever and the stud H is interposed' a helicalspring K. The other arm of said lever has a pm which enters a slot inthe lever L pivoted in a fixed bracket M. On the opposite side of thebracket M a suspended weight N is attached to leven L'. The weight 'Nis'to be of predetermined magnitude, and in order to adjust saidmagnitude it may be formed of disks a of metal, which can be variedinnumb'er as desired. Said weight operates through the levers L, Itoslide the clamp G toward the clamp C,

' and so to press the end of bar A against the end or bar B.. with aconstant pressure,

which is rendered elastic by the interposed:

spring K. To the clamps (3 G respectively are connected the terminals ofthe secondary coil 1 of a transformer-2.

The source of welding current (not shown) is connected to the switch 3which coeperates with the terminals 4, 5. Terminal 5 is connected to abrush 6 which bears upon a contact 7 on the periphery of a rotarycylinder 8 of insulating material. Terminal 1 is connected through theprimary coil 9 of said transformer to a brush l0 bearing upon a contact11 on the periphery of cylinder 8. The contacts 7 and 11 are connectedby bar 12. The cylinder 8 carries a pinion 13, with which engages a worm14: on the shaft of a motor 15, which is connected in parallel with thebrushes 6 and 10. Instead of connecting the terminal 4 to the end ofprimary "coil 9, I may connect it to a pivoted switch lever 16 whichcooperates with a plurality of contacts 17 connected to successive turnsof said primary coil, so that by suitably adj usting said lever I maycut out one or more of said turns as desired. The relation of theprimary and secondary conductors in said transformer is to be such thatthe strength of the current delivered at the secondary will beaugmented.

The operation is as follows: The pieces A, B to be welded are insertedin the clamps G, C, and the weight N is adjusted so as to cause the endof piece A to press against the end of piece B with a certainpredetermined pressure. The switch 3 being closed, a current ofpredetermined strength is delivered to said pieces at their joint. Saidstrength is. primarily'adjusted by suitably p'roportioning the primaryand secondary coils 9 and ,1, and more closely adjusted by means of thepivoted switch lever 16 operated ,to cut one or more turns of theprimary coil into or out of circuit. By

reason of'said current, the metal at the joint between pieces A, B ismelted and a Weld is produced under the pressure exerted, as al-- readydescribed. The motor 15 is simultaneously set in operation to rotate thecylinder 8. When the contact plates 7, 11 on said cylinder touch thebrushes 6, 10, circuit is closed through the bar 12 connecting saidplates, to the joint to be welded, and this closure and hence theduration of the welding current continues until by the rotation of saidcylinder, circuit is broken at said brushes. The period of rotation ofsaid cylinder'may be'determined by varying the speed of the motor 15 andin this way- I can establish the duration of the. weldingcurrent. I

. It will now be obvious that bythisapparatus 'I am enabled (1) todetermine the mechanical pressure at the joint to be Ywelded, (2) todetermine the strength of the welding current, and (3) to determine theduration of said current. And thus I may give to each of these factorsat the outset a predetermined value which may be governed by the contactareas of the. two pieces to be welded. Hence ifv theme mbers' of a lar enumber of pairs of similar pieces are to e united, the conditions beingadjusted for one pair will remain the same for all, succeeding pairs,and hence I'can effect a prac-.

tic'ally perfect weld in every pair entirely] independently of thepersonal equation of the operator. The control of the ti'mefactor ishere of especial importance, since it is preferable to use a very strongwelding current for a val may be but a fraction of a second, it ispractically impossible to control it by manually operating a switch.- Ifthe interval be made too short, an imperfect weld resultsif too long,the weldis apt to be burned and 0 again rendered imperfect, and besidesv energy is wasted. Withautomatic controlof the time factor, as abovedescribed, the

interval may be adjusted with accuracy. Instead of regulating theduration of, the welding current by varyingv the speed of the motor, thecontact pljates'7, 11 being set at an invariable distance apart, I-maydo so i by varying the distance between the-contact plates on thecylinder 8, so that current will 7 remain established for a greater orless time-the speed of the motor then being constant; or I may vary boththe speed of; the motor and the relative spacing of. the said contactplates. v a

In Figs. 2 and 3, I illustrate a circuit-. controlling device, in whichthe contact plates may be adjusted to vary the distance between themwith much accuracy. The

motor 154is hereshown mounted on any. suitable insulating 'base 18.- Theshaft 19 of worm 1% extends through the upright arms 20,21 of a bracketalso mounted on said 'base. Collars 22 on opposite sides of the bracketarm 21 prevent endwise play of-said shaft, which carries a metal disk23, 'on' the face of whichis secured a fixed arm 24 carrying the contactplate 11 and a pivoted arm 25 carryingthe contact plate. 7. On thepivoted arm is a proj'ectin plate 26' which.

receives the thrust of an a justing screw 27 loosened so that thedistance" of plate 7 from 0: 5. plate 11 may be approximately adjustedby very short interval of time. As this inter-- which passes through alug 28 on the face of lplate 23. There'is a nut and washer 29 on, the.pivot bolt' of arm 25 which is first justing screw 27 maybe used forsetting said plate 7 with greater accuracy to any desired distance.For-convenience, the brushes 10 and 6 are here carried upon blocks 30and 31 7'0 mounted on base 18 and provided with sockets 32 for theattachment of the circuit conductors. v v So long as theresistance-offered to the current at' the welding electrodes remainsconstant, the duration of the current will be regulated by the meansdescribed and will remain; corespondingly constant. But if, through anycauseas, for example, scale on the welding faces-the resistance to thecurrent increases, then the strength of'the welding current diminishes,and as it is this current which also actuates the motor, the motor speeddecreases; so that the duration ofthe current is thus automaticallyincreased to an extent proportionate to the resistance encountered atthe welding elecf tro es.

welding current, and a device actuated by said-motor and interposedin-thecircuit of f said welding current for determining the duration ofsaid current in said circuit.

3. An" apparatus for electric welding, comprising means for holding thewelded in contact, circuit connectlons to-said holding means, a motorcontrolled by the welding current, and a rotary circuit breaker actuatedby said motor. and interposed in the circuit of said welding. currentfor deter- 11o mining the duration of said current in said circuit. I II 4. An apparatus for electric'we1ding,comprising means for holding theparts to be 'welded in contact, circult connections to '1 saidholdingmeans, and two branches from" said circuit connections; a motor.controlled by the welding.- current one of said branches, a rotaxymemberactuated by said parts to be motor, connected contacts on said rotary1'20 member, and, in the other branch, fixedcontactscodperating-with.said first-named contacts.-.apparatuiforieleetric welding, com

pri'sin means-for" holding the parts to be welde incontat'zt, circuitconnections tosaid holding means, and two branchesq from said circuitconnections; a motor controlled by thewelding current in one ofsaidbranches,

a "rotary member actuated by said motor,

connected contacts on said rotary member, means for varylng the dlstancebetween sald contacts, and, in the other branch, fixed contactscooperating with said first-named con-* tacts.

y 6. An apparatus for electric welding, comprising means for determininga constant pressure of the contacts at the joint to be Welded oneagainst the other, means for de- 10 termining'the strength of theWelding current supplied to said contacts, and means controlled by saidcurrent for determining the duration of said current.

In testimony whereof I have aflixed my signature in presence of twowitnesses.

GERTRUDE T. PORTER, MAY T. MCGARRY.

